Extend observations on rodent tumors to include a few carefully selected tumors with criteria: histology, and ultrastructure supporting an epithelial origin; demonstrate the presence of greater than 15 fm of estradiol and/or progesterone receptor per milligram of protein as either cytoplasmic or nuclear form of the steroid receptor; positive identification of K-casein and a-lactalbumin by immunofluorescence techniques. Statistically analyze data from this project and compare with similar data acquired on malignant tumors examined in an ongoing study of pre- and postmenopausal breast cancer.